Slinger up oil burner apparatus

ABSTRACT

An oil burner having a main controller of the conventional form and a supply of a first fuel is independently supplied with a second more easily ignited fuel and fuel flow timing and regulating means, modulating the delivery of the second fuel to the burner during selected portions of the combustion cycle. The supply of the more easily ignitable oil significantly lessens the pollutants resulting from combustion, by providing a hotter, more complete burning than can be obtained by the heavier oil.

United States Patent 1 Ashton Oct. 8, 1974 1 1 SLINGER UP OIL BURNER APPARATUS [76] Inventor: Philip E. Ashton, 749 Yale Ave.,

Meriden, Conn. 06450 22 Filed: Apr. 17,1972

211 Appl. No.2 244,636

[52] US. Cl. 431/168, 239/214 [51] Int. Cl. F23d 11/04 [58] Field of Search 431/6, 3, 168, 162, 185,

[56] References Cited UNITED STATES PATENTS 2,214,568 9/1940 Thomas 431/185 X 2,535,316 12/1950 Ohlsson 431/3 X 3,195,606 7/1965 Stout..f. 431/185 X 3,381,896 5/1968 Winters 431/3 X FOREIGN PATENTS OR APPLICATIONS 1,021,479 3/1966 Great Britain 431/62 687,675 4/1931 France 431/62 1,102,934 10/1955 France 431/168 1,213,801 11/1970 Great Britain 1, 431/6 Primary Examiner-William E. Wayner Assistant Examiner-William C. Anderson Attorney, Agent, or Firm-Murray Schaffer [5 7] ABSTRACT An oil burner having a main controller of the conventional form and a supply of a first fuel is independently supplied with a second more easily ignited fuel and fuel flow timing and regulating means, modulating the delivery of the second fuel to the burner during selected portions of the combustion cycle. The supply of the more easily ignitable oil significantly lessens the pollutants resulting from combustion, by providing a hotter, more complete burning than can be obtained by the heavier oil.

10 Claims, 8 Drawing :Figures.

PATENTEDncr 81974 3.840.328

SHEET 30$ 3 SLINGER UP OIL BURNER APPARATUS BACKGROUND .OF INVENTION This invention relates to improvements in oil burners and is particularly concerned with facilitating the ignition of heavy fuel oils such as bunker C and No. 6 oil which are burned by them. It also relates to certain modifications in fuel flow which simplify burner maintenance.

The range of types and sizes of oil burners using heavy fuels is very wide and this disclosure will, in the interest of brevity, be chiefly concerned with the application of the invention to so called rotary oil burners. Such burners are commonly applied to boilers and kilns, etc., and vary in size from those burning 2 or 3 G.P.Il. (gallons per hour) to others burning 200 or more G.P.H.. They usually embody a hollow shaft through which oil fuel is fed to the interior of a rapidly rotating member, such as a slinger cup, carried at one end of the said shaft and located in the combustion chamber or fire box. The oil is so fed and thrown and more or less broken into small particles or droplets by centrifugal force and passage through the ambient air, that is chiefly furnished by a blower mounted on the cup shaft and discharging axially and radially thereof. This constitutes the air of combustion and carries the oil drops with it as it moves along the fire box toward the exit fuel flue.

Combustion of the oil is usually started by an electrically ignited gas flame that is directed into the path of the radially and axially moving oil drops. The gas flame is shut off after a stable oil flame has been established. The velocity of the air traversing through the fire box is enhanced as its temperature is increased by combustion. The air flow velocity and pattern'are critical to proper combustion and are arranged so that the oil drops are consumed while air suspended before impingement on the fire box walls. Initiation of combustion is very important to satisfactory burner operation.

The lower velocity of relatively cold air at start up fails to keep oil from the fire box walls; the well known difficulty of igniting heavy oil and the disturbance of the gas flame by the air draft all combine to delay ignition for an unpredictable period after being called for by the controls. Oil is of course being fed and thrown on to the fire box wall throughout the delay. When ignition finally does take place the pre-fed oil is also ignited and being in excess, relative to the air supply generated smoke and soot; further, if the fire box is hot, the excess oil may create a flash-back into the burner room. While the abnormal fuel-air condition is of relatively short duration at each turn-on the cumulative effects are most objectionable. The soot fouls the boiler flues, etc. and together with the smoke causes very serious air pollution problems. Flash-back carries the polluting material into the burner room and also deposits a very tenacious film on all adjacent surfaces.

The above mentioned conditions cause a serious economic loss and an atmospheric pollution'problem of no mean proportion. Additionally there is a persistent tendency for some of the heavy oil to form a tarry deposit that is carbonized by residual heat during shut down, on the wall and lip of the slinger cup and causes an erratic pattern of oil distribution necessitating not infrequent cleaning of the cup to correct a secondary cause of oil being thrown on to the fire box walls and erratic ignition.

It is an object of the present invention to:

a. afford clean and prompt fuel ignition in oil burners at the precise time called for by the control mechanism whereby smoke, soot and flash-back are lessened and, preferrably, entirely avoided,

b. afford a very readily adjustable means of reducing the initial oil flow toa quantity below the burners normal minimum, to prevent violent flame flare at the outset of the burning cycle, and

1 c. so modify oil feed conditions that the slinger cup is left clean and coking is avoided for relatively very lengthy periods.

These objects, others andnumerous advantages will be seen in the following disclosure of the present invention.

SUMMARY OF INVENTION According to the present invention the method and apparatus provides an oil burner having a main controller and a supply of a first fuel to which is independently supplied a second more easily ignited fuel. The burner is provided with flow timing and regulating means modulating the delivery of the second fuel during selected portions of the combustion cycle; The supply of the more easily ignitable oil significantly lessens the pollutants resulting from combustion, by providing a hotter, more complete burning than can be obtainedby the heavier oil itself during those perios of the combustion cycle when incomplete combustion is possible. I

Preferably, the easier burning fuel is a light grade oil such as No. 2 or kerosene, and it is supplied during the initial stages of the combustion cycle, and when de- According to the present inventionthere is also provided apparatus for constructing new and/or modifying existing burners with devices for carrying out the inventive steps. The apparatus comprises an independent source of a second fuel, and means to regulate its flow relative to the primary fuel.

Preferably, the apparatus includes control means for regulating the flow of the secondary fuel, both as to time and volume. Such controls are automatic and adjustable over a wide range so as to obtain a broad degree of operational control. 1 i I It is intended that the secondary fuel be used largely at either the'initial or pre-burning stage or the terminal or after burning stage of the combustion of heavy oils. Consequently, timing devices are employed tov effect such operation. In this manner the pollutant arising from poor combustion of cheap, heavy oil is reduced to almost nil.

Full details of the present invention are given in the following description and are shown in the attached drawings.

BRIEF DESCRIPTION OF DRAWINGS How the foregoing and other objects not specifically mentioned may be attained will be made clear by study of the drawings of which:

FIG. 1 is a longitudinal sectional view of a known type of oil burner,

FIG. 2 is a fragmentary sectional view of burner part comprising a modification ofparts shown in FIG. 1,

FIG. 3 is a schematic diagram showing an oil burner and its connections with a preferred embodiment of the invention,

FIG. 4 is a fragmentary longitudinal sectional view of the fuel feeding parts shown in FIG. 1 and including a part of the disclosed embodiment,

FIG. 5 is a fragmentary view of a modified inlet tubing of FIG. 2,

FIG. 6 is a diagram indicating a preferred pattern of fuel flow timing, I

FIG. 7 is a schematic drawing of a modified form of a part of FIG. 3; and

FIG. 8 is a schematic drawing of an oil burner having an embodiment of the invention as an integral part.

DESCRIPTION OF INVENTION As is well known, the heavy oil (usually No. 6) used in industrial oil burners is not easily ignited. In view of the difficulties caused thereby this invention contemplates the use of a more easily ignited substitute (say No. 2 oil) at start-up. The substitute may be used in place of the heavy oil, as a dilutent thereof or most conveniently, in both functions. The substitution is preferably of short duration, usually much less than oneminute, in view of the cost differential in favor of heavy oil. However, it may be desirable in the case of a cold fire box, to use the substitute either diluted or alone until the fire box attains a predetermined temperature before going to the normal heavy oil. This condition comes within the scope of the invention.

As the invention is readily practiced in conjunction with existing burners, i.e.: as an accessory thereto, FIGS. 1 and 2 are presented and explained as representing some of such burners to afford clear background information. It is also practical for the invention to be embodied integrally in a burner, which may be generally similar to those above mentioned, as will be later disclosed.

.FlGfl is generally representative of a rotary oil burner 10, of well known type having a hollow horizontal shaft 20, carrying a driving pulley 22 and being supported on suitable bearings 24 in a gear case 26 whereon may be mounted an electric motor and belt organization (not shown) suited for driving said shaft through said pulley. A shrouded centrifugal air blower 28 is mounted on said shaft within a housing 30 secured to case 26; the said housing has a radially extending flange 32 by which the burner may be secured to a fire box end plate 34 that usually has a refractory liner 36. The housing 30 also embodies an air intake 38 having a butterfly damper 40, it further embodies a discharge duct 42 placed co-axially of shaft and surrounding an oil slinger cup 44 which is secured to the said shaft and the whole is arranged so that air from said blower is discharged in an annular pattern around said cup. Worm gear 46 is secured to shaft 20 within the case 26 and meshes with a gear 48 for driving an oil pump 50 (not shown in FIG. 1) through shaft 52. The left-hand end of shaft 20 terminates adjacent to a bracket 54 that comprises part of case 26; it is fashioned to firmly support a fuel feeding structure 56 by means of mating flanges 58 and 60. The said structure 56 comprises a hollow head casting 62 wherein is secured a rigid steel tube 64 located co-axially of said shaft 20 and passing therethrough without contact. The said tube is closed at its right hand end by a so called nozzle 66 having an orifice 68 through which oil may be discharged into cup 44. The head casting 62 has an inlet port 70 and it further has an opening 72 substantially coaxial with tube 64 which is closed by a threaded plug 74.

In operation oil is delivered bythe pump 50, through a tube 76 to port 70 whence it passes along tube 64, through orifice 68 and into the interior of the rapidly rotating cup 44. Oil flow is controlled in ON and OFF fashion by a conventional electrical solenoid valve 78, which is ON, or open, when energized. Oil discharged into cup 44 is thrown overthe lip thereof by centrifugal force and is normally broken into a mist by radial dispersion and its passage through the air in preparation for combustion which is initiated by a gas flame directed into the path of the dispersing oil. All of which is common knowledge among those versed in the art.

FIG. 2 illustrates a minor modification in the mode of feeding oil to the slinger cup 44. Here the hollow shaft 80 passes through a rotary seal-82 in bracket 84 which is in general an equivalent of bracket 54, described earlier. Oil is fed to said shaft through tube 86 and solenoid valve 78 and is discharged into an elbow 88 that surrounds seal 82 and has oil tight contact with bracket 84. Oil flows from the elbow 88 through hollow shaft 80 and into cup 44 via a nozzle 90 at the right hand end of the said shaft. Operation is similar to the earlier described mode. There are other variants in the way oil is fed to cup 44 or an equivalent thereof but as they haveno serious import relative to the use of the invention, they are not described here.

The above described burners usually have a main controller (not shown) brought into operation when a thermostat or other. device closes an electric'circuit to call for heat. When this occurs, the main controller then in sequence switches on the burner motor which also drives the fuel pump 50, lights the gas jet pilot'and after a time lag, called a pre-purge energizes solenoid valve 78 allowing fuel to flow to cup 44 for burning. Oil quantity is controlled by mechanisms, not here of interest, to afford an initial low firing rate and after a short time to increase the firing rate to maximum. The burner runs during BURN until heat demand is satisfied whereon the thermostat or its equivalent opens its circuit to the main controller which then deenergizes solenoid valve 78 shutting off fuel but allows the burner motor to run for a short period (called post-purge) usually of 30 to 45 seconds duration to clear the cup 44 of any oil remainder and finally shuts down. However, oil may later dribble from the hollow shaft and because of residual heat in the fire box some is carbonized on cup 44; some may also drip to the lower side of duct 42 where it carbonizes and distorts the air passages therethrough.

When combining a burner of the class described with the present light oil feeding devices the electric leads from the above mentioned main controller are disconnected from solenoid valve 78 and taken to subcontroller (to be described later) so that it and not the said solenoid valve is dominated by the main controller. The current so diverted serves as a signal to initiate operation of the subcontroller 110, it is hereafter termed signal or signal current. Note that all solenoid valves here involved are ON or open when energized and OFF or shut when de-energized.

FIG. 3 shows schematically the oil burner 10, the light oil supply means and the subcontroller 110 which embodies the electrical controls. The burner has heavy oil pump 50, hollow shaft 20, slinger cup 44 and the solenoid valve 78 controlling heavy oil delivery from pump 50 as earlier described. The light oil supply means comprise motor-pump unit 92 for drawing light fuel through pipe 94 and delivering it via solenoid valve 96 and throttle valve 98 to pipe 100 which is connected within the burner organization to hollow shaft as later explained. Solenoid valve 96 is desirable but not essential and is connected in parallel to unit 92 to give a sharp oil cut-off when de-energized. The said means also comprises a by-pass line 102 around pump unit 92 in which line are pressure relief valves 104 and 106 together with the solenoid valve 108 connected in parallel with valve 78. With solenoid valve 108 deenergized, valve 104 holds pump delivery pressure to throttle valve 98 at a desired uniform valve but when valve 108 is energized the valve 106, set to open at a lower pressure than valve 104 will govern the pressure at said throttle valve. This makes two fuel flow rates available for one setting of valve 98. subcontroller 110 is preferrably a unitary structure comprising the com ponents shown within the large broken line rectangle. It includes a 3PDT relay 112, energizable by signal current from the main control box; a conventional 60 second cycle motor driven timer 114 shown within the chain line rectangle and having three switches operated by cams (not shown); a SP.ST manual reset normally closed relay 116 whose coil is connected to three paralleled normally open thermally responsive delay action switches 118, 120 and 122 commonly known as delay relays, any one of which, if it closes, will trip relay 116, breaking line current and de-energizing pump 92, solenoid valves 78, 96 and 108, shut off all fuel to the burner. The drawing shows the subcontroller deenergized and ready to start a burning cycle on receipt of a signal from the main controller.

The subcontroller 110 is connected to Line as indicated. When relay 112 is energized by signal current from the main controller which enters via terminals 124, line current goes through contact 126 and switch 128 to timer motor 130 and, through switch 132 to the subcontrollers pump terminal 134 and thence to pump 92 and solenoid valve 96, causing light oil to flow at a pressure determined by relief valve 104 through throttle valve 98 and pipe 100-to the burner which as indicated by the delivery of the signal, has completed its pre-purge and is ready to be lit by the usual gas flame. After a suitable pause, during which the light oil flame is established, the timer closes switch 136 sending current to terminal 138 and on to solenoid valve 78 which opens to allow heavy fuel to flow from pump 50 to be burned. Solenoid valve 108 opens at the same time as valve 78 and thereby reduces the light oil pressure. This dual pressure arrangement allows a relatively large flow of light oil at first and then when light and heavy oils are combined, the flow is still not excessive. After the flame of the combined oils has become established, the timer changes the condition of switch 128 so that its blade engages contact 140 and opens the connection with contact 126, thereby de-energizing the timer motor 130, pump unit 92 and solenoid valve 96 which shuts off the light oil and leaves the burner on BURN with its normal fuel. When the heat demand has been satisfied, the thermostat or its equivalent opens its circuit to the main controller, whereon signal current is cut off and relay 112 reverts to the state shown in FIG. 3, directing line current through contact 140 to timer motor 130, pump unit 92 and solenoid valve 96 causing the timer to again start running and light oil to be furnished to the burner at its lower'pressure. After a very brief period, usually about 2 or 3 seconds, the timer opens switch 136 which de-energizes solenoid valves 78 and 108 whereby heavy fuel is shut off from the burner and the light oil pressure is raised to its higher value. This condition, (post burn flush) continues long enough, usually about 5 to 8 seconds, when switch 132 is opened and light oil shut off. This period is long enough for the heavy oil to be flushed from the slinger cup, leaving only the light oil, if any, on its surfaces at the end of the post purge period. The light oil being (a) volatile and (b) of very low viscosity, leaves the cup clean and eliminates practically all c'arbonization. The post burn flush also leaves the approaches to the slinger cup clear of heavy oil so that at the start of the next op- 4 erating cycle there is no hesitation in the appearance of the light oil. How the light oil delivery pipe is con-v nected within the burner organization is made clear by FIGS. 4 and 5. FIG. 4 shows the fuel feeding structure of FIG. 1, but having solid threaded plug 74 replaced by a hollow plug 142 wherein is secured tube 144 that passes inside tube 64 to a point adjacent nozzle 66. Plug 142 has a threaded port 146 to which pipe 100 of FIG. 3 may be connected without interference with the heavy oil supply connection. FIG. 5 shows the elbow 88 and solenoid valve '78 of FIG. 2 without change but tube 86 has been replaced by a tee fitting 148 that affords access, down stream of the valve 78, to the interior of elbow 88 and whereto pipe 100' may be connected to deliver light oil. I

FIG. 6 is a diagram covering the sequence of events incident to a burning cycle and without relating to the pre-purge and post-purge periods. The disc represents the timers (114) running period plus the indefinite BURN period. The sectors represent:

A. Light oil alone at the higher pressure (wide line) B. Heavy oil plus light oil at lower pressure (narrow line) C. BURN with heavy oil alone. Timer shut off by switch 128 D. Heavy oil plus light oil at lower pressure E. Light oil alone at the higher pressure (post burn flush) F. All fuel off. Timer coasting to end of its cycle when switches 128 and 132 will revert to conditions shown in FIG. 3 and timer will stop.

Time values are not rigid and may be adjusted to suit individual installations. They may average A. 3-5 seconds, B. 2-4 seconds, C. indefinite, D. 2-3 seconds, E. 4-8 seconds, F. balance of timers cycle.

Subcontroller IIO-embodies certain safety arrangements. During period B switch 136 is closed and switch 128 is in the condition shown in FIG. 3; should the signal go off at this time relay 122 will take the condition illustrated and current will pass, from the line leading to valves 78 and 108, to relay blade 150, contact 152 and so through switch 128 to the timer causing it to complete its cycle and shut off all fuel while so doing. Without the relay action described, control over the heavy oil flow would be lost as the timer would be stopped with switch 128 in the illustrated conditionand nothing available to restart it. The combination of the lower pole of relay 112 with delay action switch 118 affords further protection against a run-away fire. Relay 112 is energized during periods A, B and C and contact 154 is inert so that delay switch 118 is held inactive during the indefinitely long BURN time. However, the heater of said delay switch is in circuit with valves 78 and 108 when relay 112 is in signal off position; if said valves are then energized beyond the designed delay of switch 118 which is in excess of period D, the said switchs contacts will close, trip relay 116 and cause complete shut down. Delay switch 120 having its heater in parallel with pump 92, is timed for the pump to run through periods A, B, D and E but if it is in circuit apprecially longer it will close its contacts, trip relay 116 and cause shut down. Delay switch 122 is in parallel with the timer motor 130 and if the latter is energized, for any reason, apprecially beyond its normal cycle time, the said switch will energize relay 116 and cause complete shut down. The following delay times appear satisfactory; switch 118, 20 seconds; switch 120, 30 seconds and switch 122, 75 seconds.

As indicated above, periods D and E trespass on the burners post purge time as apportioned by the main controller without harm, as the flushing action aids the purges cup cleaning function. But, if the amount of oil in the burners passages is too large to be displaced by light oil in the time available, it becomes necessary to creat a time-lapse between thermostat opening and signal cut-off to allow the desired displacement. This is done by modified subcontroller 156 as shown in FIG. 7 which shows it unenergized. Here, instead.of going directly to the main controller, the thermostat lines go to it via the subcontroller 156 where receipt of a signal from the main controller causes the following events:

a. the thermostat lines are bridged by a relay so as to make the main controller insensitive to the thermostat.

b. the thermostat is reconnected within the subcontroller so as to dominate the latters functions.

c. an additional switch in the timer holds period E as long as desired and then restores the thermostats regular functions whereon the main controller initiates post purge and shut-down in the usual way.

Certain parts used in subcontroller 110 are used here without change in identity or function. Timer 158 is like timer 114 but for a fourth switch 160. Relay 162 is identical in all ways including functions with relay 112 except for its coil being energized by line instead of signal current. Considering operations: when the thermostat (or other heat demander) closes, the following happens:

]. a circuit is closed from the thermostat 164, via terminals 168 contacts 170 terminals 172 and thence to main controller which v 2. puts burner through its normal start-up sequence to end of pre-purge when 3. signal current received via terminals 174 from main controller energizes relay 176 so that blade 178 bridges or shorts" lines 180 and 182 making main controllerinsensitive to thermostat and 4. blade 184 closes a line circuit through coil of relay 186 whereon 5. blades 188 and 190 separate the thermostat from lines 180 and 182 and 6. connect it to the coil of relay 162 making the latter responsive to said thermostat and to be energized by line current so that ll. the timer restarts, initiating period D, which is followed by period E but 12. lines 180 and 182 are still bridged and main controller insensitive so that post-purge can not be started and timer may be set to run long enough to entirely free burner of heavy fuel after which 13. switch opens to break signal current to relay 176 which when de-energized will 14. open bridge across lines and 182 and deenergize relay 186 which 15. will reconnect the now open thermostat to lines 180 182 to main controller that will 16. start the normal post-purge sequence while the 17. timer completes its cycle during which switch 160 is reclosed and which is ended by switches 128 and 132 reassuming the position shown, ready for a new operating cycle, to be started when called for by the thermostat.

It should be here noted that the timer values given for delay switches 120 and 122 will have to be reviewed where they are used with subcontroller 1'56; new'values will depend on the duration of the post burn flush. The subcontroller just described may also'be used where the main'controller is not arranged to allow a c onventional post-purge, so as to provide the highly desirable flushing actions described.

Practicing the present invention requires (a) a source of light or easily ignited fuel, (b) means to regulate its flow in conjunction with the normal or heavy fuel and, (c) the means to control, timewise, the sequence of certain events involving (a) and (b). The foregoing disclosure is of a preferred structure but many variations are practical. For instance, instead of using solenoid valves, one could use mechanical valves actuated by the cams of a sufficiently rugged timer; the pump unit (92 herein) might embody a reducing gear and so comprise the timer; the pump unit might be replaced by a gravity head or a pressurized tank. Solenoid valve 108 could be eliminated when furnace conditions permit and another modifcation would be the use of a modulating mixing valve to govern the transition from one fuel to another.

The foregoing describes an organization that may readily be added to an existing burner. It is, however, practical to embody the invention integrally-within a burner. Such a case is described below with a reference to FIG. 8. In this case the construction shown comprises the burner 192, which lies to the left of the broken line and is under the control of a main controller (not shown) as above described re FIGS. 1 and 2. It also comprises a subcontroller 194, that lies to the right of the broken line and is responsive to a signal from the main controller. No attempt has'been made to show such other items as ignition parts, viscosity valves, high and low fire controls, driving motors, etc. as they are not of direct concern and are well understood in the art. The burner 192 comprises a pump 196 having a capacity in excess of burner usage and similar to the earlier mentioned pump 50. The pump 196, is arranged to draw a first, or heavy oil through pipe 198 or to draw a second or light and more easily ignited oil through pipe 200, either oil being received from any convenient source, not shown. Oil is delivered by the said pump through pipe 202, normally closed solenoid valve 204 and hollow shaft to slinger cup 44 as earlier described; a throttle valve 206 is preferrably located down stream of said solenoid valve, as shown. A selector valve 208 is interposed at the junction of pipes 198 and 200. As shown in the drawing, the former pipe is closed by valve shutter 210 while pipe 200 communicates with said pump making light oil available to it, but if the said shutter is turned CCW it will close pipe 200 and open pipe 198 to make heavy oil available to the pump. An adjustable relief valve 212 may be located as shown to afford greater resistance to the flow of heavy oil than is offered to the flow of light oil through pipe 200. This arrangement aids in the maintaining of desired proportions of the mix of fuels while the said valve shutter is being moved from its one position to its other; it is also assures little leakage of heavy oil past the shutter 210 when it is in the position shown. An adjustable relief valve 214 is located in pipe 216 which is teed into pipe 200 and forms a bye-pass loop around pump 196 that is open when shutter is in the position shown. Another adjustable relief valve 218 is located in pipe 220 whereby heavy oil may be returned to its source when shutter 210 is moved to open pipe 198 and close pipe 200. Valve 214 is set to open at lower pressure than valve 218 so that with the parts m the position shown light oil may be pumped and held at a lower pressure while being bye-passed around the said pump than would obtain if heavy oil were being pumped and pipe 200 closed by selector valve 208; a check valve 222 prevents heavy oil at its relatively high pressure from opening valve 214 and flowing down pipe 200 in reverse to normal direction. In brief, when light oil is being pumped the excess over burner consumption is recirculated at relatively low pressure and when heavy oil is being pumped at a relatively high pressure, the excess is returned to the heavy oil source. This dual pressure affords two oil flow rates at any setting of throttle valve 206.

The dash-pot cylinder 224 has a piston and rod assembly 226 which may be moved to the left, from the position shown and against the urging of spring 228 by oil pressure transmitted from pipe 202 through pipe 230, normally closed solenoid valve 232, adjustable restriction 234 to the cylinder 224. Valve arm 236 is secured to selector valve shutter 210 at one end and its other end is suitably connected to the said piston rod which, when moved to the left from the position shown partially rotates the said shutter to open pipe 198 while closing pipe 220. During such valve movement both pipes are open to the suction of pump of pump 196 and there is no interruption in oil flow; it is then that the flow resistance of valve 212 determines the oil mixture. This makes it possible to avoid any large proportion of heavy oil in the fluid in cylinder 224 and to maintain a fairly uniform viscosity and attain a reasonably constant dash-pot timing action which can be varied by restrictions 234 and 240. Piston and rod assembly 226 may be returned from the left ward position, to that shown in the drawing, by spring 228 if solenoid valve 232 is closed and normally open solenoid valve 238 is permitted to open when oil in the said cylinder will flow through adjustable restriction 240 and on into pipe 242 leading to the suction side of pump 196. Such restoration of piston and rod to the position shown in the drawing will also restore valve 208 to the position shown, where light oil is available to the said pump. Note that solenoid valve 232 has to be energized to be close while solenoid valve 238 has to be energized to be open.

The subcontroller 194 is preferrably a single unit; it comprises a DPDT relay 244 energizable by signal current for switching purposes, a SPST relay 246 that cooperates with a normally closed thermally responsive delay switch 248 to hold solenoid valve 204 open for a predetermined time after the signal has gone OFF, thus affording the highly desirable post-burn Flush Period previously described. Another delay switch 250 that is normally open serves, in case of need, to short circuit line fuze 252 and so affords a safety function. The drawing shows the device deenergized. When heat is required, the main controller switches on the burner motor (not shown) which drives pump 196, ignites the gas pilot flame, and after pre-purge, sends signal current to terminals 254. Terminals 256 receive line current from the burner motor or other convenient source switched ON and OFF by the main controller. Switch 248 is preferrably arranged to open after being incircuit about 10 15 seconds while switch 250 preferably closes after being in circuit about 60 seconds. When a burner operating cycle starts, line current passes through fuze 252, relay blade 258, contact 260 and the heater of switch 248 which will open in due time, but without effect as it has no function'until after the burn period. Following the normal pre-purge period the main controller will send signal current and energize relay 244 when the following events will take place:

a. relay blade 262 engages contact 264 and linecurrent will open solenoid valve 204 whereon lightoil, which is available on account of selector valve 208 being in the position shown, passes through throttle valve 206 and on in the usual manner via hollow shaft 20 to cup 44 to be burned while, simultaneously,

b. relay blade 258 engages contact 266 and current opens normally closed solenoid valve 232 while closing normally opens solenoid valve 238; this admits oil under pressure to cylinder 224 while isolating it from the suction side of pump 196, whereon piston and rod assembly 226 starts moving to the left at a rate decided by restriction 234 to gradually change the condition of selector valve 208 from the light oil position shown to the other positions, not shown, where only heavy oil is delivered as earlier explained, and the BURN period starts. At the same time c. blade 258 has left contact 260 and delay switch 248 recloses after a few seconds. The said switch is in parallel with solenoid valve 204 and current is free to pass through the coil of relay 246 which causes blade 268 to engage contact 270 to close a second circuit to said solenoid valve, thus feeding it from the control of relay 244.

d. As above stated, BURN is in process, piston and rod 226 are at their extreme leftward position, selector valve 208 is directing heavy oil to pump 196 to be burned and the heater of delay switch 248 is in open circuit while the switchs contacts are closed. But, as soon as heat demand is satisfied, the main controller terminates the signal and e. relay 244 is de-energized, blade 258 leaves contact 266, this de-energizes solenoid valve 232 and shuts pipe 230 from pipe 202; it also de-energizes normally open solenoid valve 238 which puts pipe 230 in communication with pipe 242, unsealing cylinder 224 and allowing spring 228 to return piston and rod 226 and selector valve 208 to the positions shown, cutting off heavy oil and restoring light oil flow to the burner which now enters the Post-burn Flush Period: at the same time f. blade 258 re-engages contact 260 causing heating of delay switch 248, while blade 262 has left contact 264, leaving solenoid valve 204 energized solely through relay 246. After its predetermined interval the said delay switchs contacts open and break the line circuit through the coil of relay 246 which then opens its circuit to solenoid valve 204, all fuel is cut off from cup 44 and the flame goes out. The burner then completes its post-purge Period and shuts down. The normally open delay switch 250 has its contacts connected across the line so that if they close, fuze 252 will be opened by the resulting short circuit. Its heater circuit is in parallel with that of delay switch 248 but its delay setting is much longer than that of the latter and in normal usage its contacts never close, but if switch 248 fails to respond when energized after BURN, switch 250 will close and cause an emergency shut-down. it may be pointed out at this time that the delay setting of switch 250 is such that it will not close during the pre-purge period even though switch 248, with its short delay, goes to contact open" condition.

If desired, a normally open delay action switch may be placed in the line to soleoid valves 232 and 238 to replace restriction 234 and 240 to control the duration of the light oil burning period before hydraulic action initiates the movement of selector valve 208 from the position shown. To affect this, the delay switchs heater would be connected from contact 266 to the return line at any convenient point while its contacts would be interposed between the said contact 266 and the said solenoid valves. Duration of the light oil burning period would depend on the selection of a commercially available switch. These have delay ranges running from I second to over 1 minute.

What is claimed:

1. The combination comprising rotary type oil burner having an oil slinger cup for dispersal of fuel into a combustible mist, an orifice opening into the interior of said cup for normally burning a first fuel and having a main operating controller for regulating the normal combustion cycle of said burner, a source of a second fuel more easily ignited than said first fuel, and fuel flow timing and regulating means arranged and adapted for modulation of the delivery of said second fuel to the orifice of said burner independently of said first fuel and in part in seriatim therewith during selected portions of any combustion cycle whereby the quantity of soot and air pollutants resulting from said combustion of said first fuel is at least lessened by the improved combustion of said second fuel.

2. The combination according to claim 1, wherein said timing and regulating means is arranged to feed said second fuel during the initial portion of said combustion cycle.

3. The combination according to claim 1, wherein said timing and regulating means is arranged to feed said second fuel during the terminal portion of said combustion cycle.

4. The combination according to claim 1, wherein said timing and regulating means includes means for adjusting the volume of said second fuel as it is fed to said burner relative to said first fuel.

5. An oil burner of the class described having a nonrotating passage for delivering fuel oil through an ejection orifice, a rotary slinger cup open to said orifice for the delivery of fuel to a fire-box, a tube inserted within said passagehaving one end accessible for connection to a source of fuel other than that used as a fuel-in-chief and having its other end within said passage adjacent said orifice whereby the orifice of said passage may expeditiously be cleared of said fuel-in-chief, said tube being appreciably smaller in cross section than the cross section of said passage so as to afford a way for the flow of said fuel-in-chief.

6. Apparatus for operative connection to a burner having'a rotary slinger cup provided with a nozzle orifice opening into the interior thereof for heavy oil, said burner having an operating controller and comprising conduit means through which a relatively light oil may flow from a receptacle to said burner upstream of said orifice, first means to start and stop said flow, second means arranged and adapted to afford a control for connection to a valve component of said burner for starting and stopping the flow of heavy oil thereth'rough and timing means for interconnection with and responsive at least in part to said controller, said timer being arranged and adpated for operational connection to said first and second means to operatively control the flow of said oils to said burner for combustion in designed sequence to comingle for at least some period consequent upon a change from one oil to the other.

7. The apparatus according to claim 6 which further includes means arranged and adapted to afford a plurality of rates of flow of said light oil to said burner.

8. Apparatus for operating an oil burner having a rotary slinger cup provided with a nozzle orifice opening into the interior thereof and a controller for regulating the operation thereof, a source of a first fuel oil, an independent source of a second fuel'oil, and means for conducting the flow of oils to the orifice of said burner comprising first electrically operated means for starting and stopping the flow of said first fuel to said burner, a second electrically operated means for starting and stopping the flow of said second fuel to said burner, a third electrically operated means arranged and adapted to afford a plurality of rates to the flow of said second fuel'to said burner, an electric timing means interconnected with and responsive, at least in part, to said controller and arranged and adapted to control the flow of electric current to said first, second and third electrically operated means in a desired sequence whereby said fuels may be burned by said burner in a predetermined arrangement. g

9. The apparatus according to claim 8 wherein said electric timing means embodies part of a circuit between the closable contacts of a heat'demand responsive structure and said controller, said timing means being receptive to signal current and on receipt of such signal current, renders said controller insensitive to said structure, closes electric circuits through a plurality of relay contacts and thereby sets in motion a motorized switching organization which affords said fuel flow timing and regulating functions, and affords a predetermined time' delay between the opening of said closable contacts when such heat demand has been satisfied and the transmission of the information thereof to said controller whereby said burner is afforded a post-burn flush period that is separate from its normal post purge period.

10. The combination comprising an oil burner having a rotary slinger cup provided with a nozzle orifice opening into the interior thereof suited for burning in a regulated combustion cycle a first fuel and having a source thereof and a second fuel also having a source thereof and fuel flow regulating means arranged and adapted to regulate the delivery to the orifice of said burner of each of said fuels independently of the other, said regulating means being further arranged and adapted to afford such delivery in a predetermined sequential program during selected portions of a combustion cycle whereby the quantity of soot and of air pollutants resulting from combustion characteristics of said second fuel. 

1. The combination comprising rotary type oil burner having an oil slinger cup for dispersal of fuel into a combustible mist, an orifice opening into the interior of said cup for normally burning a first fuel and having a main operating controller for regulating the normal combustion cycle of said burner, a source of a second fuel more easily ignited than said first fuel, and fuel flow timing and regulating means arranged and adapted for modulation of the delivery of said second fuel to the orifice of said burner independently of said first fuel and in part in seriatim therewith during selected portions of any combustion cycle whereby the quantity of soot and air pollutants resulting from said combustion of said first fuel is at least lessened by the improved combustion of said second fuel.
 2. The combination according to claim 1, wherein said timing and regulating means is arranged to feed said second fuel during the initial portion of said combustion cycle.
 3. The combination according to claim 1, wherein said timing and regulating means is arranged to feed said second fuel during the terminal portion of said combustion cycle.
 4. The combination according to claim 1, wherein said timing and regulating means includes means for adjusting the volume of said second fuel as it is fed to said burner relative to said first fuel.
 5. An oil burner of the class described having a non-rotating passage for delivering fuel oil through an ejection orifice, a rotary slinger cup open to said orifice for the delivery of fuel to a fire-box, a tube inserted within said passage having one end accessible for connection to a source of fuel other than that used as a fuel-in-chief and having its other end within said passage adjacent said orifice whereby the orifice of said passage may expeditiously be cleared of said fuel-in-chief, said tube being appreciably smaller in cross section than the cross section of said pAssage so as to afford a way for the flow of said fuel-in-chief.
 6. Apparatus for operative connection to a burner having a rotary slinger cup provided with a nozzle orifice opening into the interior thereof for heavy oil, said burner having an operating controller and comprising conduit means through which a relatively light oil may flow from a receptacle to said burner upstream of said orifice, first means to start and stop said flow, second means arranged and adapted to afford a control for connection to a valve component of said burner for starting and stopping the flow of heavy oil therethrough and timing means for interconnection with and responsive at least in part to said controller, said timer being arranged and adpated for operational connection to said first and second means to operatively control the flow of said oils to said burner for combustion in designed sequence to comingle for at least some period consequent upon a change from one oil to the other.
 7. The apparatus according to claim 6 which further includes means arranged and adapted to afford a plurality of rates of flow of said light oil to said burner.
 8. Apparatus for operating an oil burner having a rotary slinger cup provided with a nozzle orifice opening into the interior thereof and a controller for regulating the operation thereof, a source of a first fuel oil, an independent source of a second fuel oil, and means for conducting the flow of oils to the orifice of said burner comprising first electrically operated means for starting and stopping the flow of said first fuel to said burner, a second electrically operated means for starting and stopping the flow of said second fuel to said burner, a third electrically operated means arranged and adapted to afford a plurality of rates to the flow of said second fuel to said burner, an electric timing means interconnected with and responsive, at least in part, to said controller and arranged and adapted to control the flow of electric current to said first, second and third electrically operated means in a desired sequence whereby said fuels may be burned by said burner in a predetermined arrangement.
 9. The apparatus according to claim 8 wherein said electric timing means embodies part of a circuit between the closable contacts of a heat demand responsive structure and said controller, said timing means being receptive to signal current and on receipt of such signal current, renders said controller insensitive to said structure, closes electric circuits through a plurality of relay contacts and thereby sets in motion a motorized switching organization which affords said fuel flow timing and regulating functions, and affords a predetermined time delay between the opening of said closable contacts when such heat demand has been satisfied and the transmission of the information thereof to said controller whereby said burner is afforded a post-burn flush period that is separate from its normal post purge period.
 10. The combination comprising an oil burner having a rotary slinger cup provided with a nozzle orifice opening into the interior thereof suited for burning in a regulated combustion cycle a first fuel and having a source thereof and a second fuel also having a source thereof and fuel flow regulating means arranged and adapted to regulate the delivery to the orifice of said burner of each of said fuels independently of the other, said regulating means being further arranged and adapted to afford such delivery in a predetermined sequential program during selected portions of a combustion cycle whereby the quantity of soot and of air pollutants resulting from combustion characteristics of said second fuel. 